For a wonderful BYOB in a small, intimate setting, I recommend Sola in Bryn Mawr.I have seen several tables where they have catered to that large a group.The food is excellent and, of course, you can have your choice of steak or seafood, etc. In fact, they have a famous surf and turf (filet mignon and lobster dish) that you might make sure they have on the menu before you get there.Hint: If you decide to go there, park across the street at the Acme Market lot. Do NOT park in the lot next to the restaurant -- you will be towed!

Glenmorgan is OK but the atmosphere isn't great for dinner in my opinion. It had a diner feel on a saturday night and we felt out of place. However, next door is a Fleming's Steakhouse and a Susanna Foo. Fleming's might be what you are looking for.

Problem with wonderful Fleming's is that the steaks start at $30+ and this doesn't leave much room for anything else if you plan to have a glass of wine and need to tip.If you feel you could up the price a bit, I highly recommend Fleming's.However, with Susannah Foo you can make it. And this place is really quite lovely and the Asian food is very good. I didn't mention it because you seemed to want to stick with American fare.

To get a private room, you might want to consider the Old Guardhouse in Gladwyne, Blush or Tango in Bryn Mawr, or (more of private nook) 333 Belrose, but these are not byobs. I think that Spamps in Conshohocken also has a private room, but I've never eaten there. For byobs, in addition to Sola (a favorite), check out Cafe Fresko in Bryn Mawr and Blackfish in Conshohocken.

Although it is predominantly French-American, I highly recommend "George's" in Wayne, PA. It's on West Lancaster Avenue and is an offshoot restaurant by the famed Georges Perrier. They have a private room upstairs; I researched it for a client of mine (I'm an event planner). Last I heard, a plated dinner is $45/pp and they offer steak and seafood. Beautiful setting; beautiful amosphere. Very polished, but relaxed.